Electrical connector



Oct. 21, 1969 E. A. LINK 3,474,386

ELECTRICAL CONNECTOR Filed June 10, 1968 INVENTOR.

Edwin A. Link 22 BY L020 8 Barry Attorneys United States Patent US. Cl. 339-60 16 Claims ABSTRACT OF THE DISCLOSURE Disclosed herein is an electrical connector for high voltage cables having arc extinguishing devices associated with the ends of electrically conductive elements mounted in insulating members having cooperating surfaces to produce a seal on connection of said elements.

RELATED APPLICATION This application is a continuation of my copending application on the Electrical Connector, Ser. No. 343,527, filed Feb. 10, 1964, and now abandoned.

BACKGROUND OF THE INVENTION The electrical hazards commonly associated with the maintenance and repair of high voltage cables are well known. One of the principal hazards is the electric are which results on disconnection or breaking of a high voltage cable. This hazard has been particularly significant in the development of underground power distribution systems where the transformers are mounted at ground level and permanent type cable terminations have been made in order to obtain maximum safety. This has complicated the maintenance and repair of such systems because specially designed switch gear had to be located within the inaccessible compartment of the transformer in order to safely interrupt load current. It had been long recognized that faster and simpler means was required in order to interrupt load current with a minimum of interruption of customers service. If the interruption of load current could be made at the cable termination in the accessible compartment, then cable faults could be isolated in a matter of minutes once they have been located.

SUMMARY OF THE INVENTION The invention disclosed herein provides an electrical connector for disconnecting high voltage cables that can be used with a maximum of safety for disconnecting any high voltage cable. This electrical connector includes a plug having an insulated follower associated with the end of an electrically conductive member and a receptacle having an insulated sleeve positioned at the entry end of an electrically conductive sleeve. The insulated follower and insulated sleeve are both made of an arc extinguishing material which is activated on drawing an arc across the gap between the two conductive members on disconnection of the electrically conductive members. The heat of the arc is dissipated by the arc extinguishing material, setting up a de-ionized zone in the small space remaining between the follower and sleeve. This de-ionized zone will interrupt current flow in two to four cycles after separation is made at the plug and as a consequence extinguishes the arc.

The plug hood is molded from an elastomer material having elastic characteristics which are important in several respects A hook-eye provided in the hood provides ice an energy storage in disconnecting the plug from the receptacle due to the elasticity of the material similar to the action of a spring once the other end is released. An annular groove is provided on the end of the receptacle which cooperates with a ring in the plug to provide a holding action on disconnection of the plug from the receptacle. The plug and receptacle are further designed for a close moisture-tight fit that adds some holding force due to the vacuum set up between the plug and receptacle on disconnection. On release of the plug from the receptacle, a snap action occurs which results in practically instantaneous disconnection.

Cable termination at the plug is made by stripping the concentric stranding back from the end of the cable and removing the conductive sleeve to bare the high voltage insulation. A terminal lug is crimped to the end of the conductor and inserted into a recess molded in the plug hood. The recess is filled with a grease-like insulating material which will fill the voids around the end of the cable in the recess. An electrically conductive member is screwed into the terminal lug within the plug and conductive tape is wrapped around the end of the preformed stress cone in the plug. Termination is then complete. This termination arrangement has been found to be particularly advantageous because of its low cost and simplicity while providing a maximum of safety for handling the plug after termination.

Other objects and advantages will become more readily apparent from the following detailed description when read in conjunction with the accompanying drawings, in which:

FIG. 1 is a side View of an electrical connector in section with the plug and receptacle in engagement.

FIG. 2 is a view similar to FIG. 1 showing the plug and receptacle disengaged.

FIG. 3 is a view of a modified connector showing the electrically conductive members electrically connected and the insulated members disengaged.

FIG. 4 is similar to FIG. 3 showing the electrically conductive members disengaged and the insulated members engaged.

For purposes of illustration and description, the electrical connector shown is described in connection with its adaption for use with a ground level transformer. It should be obvious that the use of such a connector is not so limited. The concept of this electrical connector can be used in any application where it is desirable to eliminate the hazard of an electrical are when breaking or disconnecting a high voltage electric cable. High voltage as used herein refers to cables designed to carry one thousand volts or more.

Referring more particularly to the drawing, an electrical connector is shown which includes a plug assembly 10 and a receptacle assembly 12 each having a surface that produces a seal on connection. Each assembly includes an electrically conductive element which produces an arc on disconnection from the other element and is provided with means for extinguishing the are produced on disconnection of the electrically conductive elements mounted in the assembly.

More specifically, the plug assembly includes a first member or hood 14- molded from an insulating material such as elastomer rubber and is providedwith a hook eye 17, an electrical connection recess 16 and a cable termination recess 18. In the drawing, these recesses are shown transverse to each other but they could be coaxially arranged if desired. The receptacle assembly includes second member or bushing 40 made from any of the known organic insulating materials as well as the inorganic materials such as glass or porcelain. The bushing is provided with a central recess 42 and a flange 44 having a threaded section 46 for mounting on a panel 52.

Cable termination is made in the plug assembly by inserting the end of a high voltage cable 22 into the cable termination recess. The cable is prepared for termination by stripping the concentric stranding 23 back from the end of the cable and grounding it by any appropriate means. The conductive sleeve 25 is removed to bare the high voltage insulation 27. A terminal lug 24 is crimped to the end of the cable and has a nut 28 secured to the end. The cable termination recess is filled with a grease-like material prior to insertion of the cable and upon insertion will fill the voids around the cable. The terminal lug is secured in the recess by screwing a first electrically conductive element or member 26 into nut 28 so that it projects into recess 16. An electrically conductive tape is then wrapped around the end of the recess which forms a stress cone with the preformed shape of end of the hood.

In the embodiment shown in FIGS. 1 and 2, an insulating means or member 30 is secured to the end of the electrical conductive element 26. The insulating member 30 can be made from any of the well-known arc extinguishing insulating materials, such as hard vulcanized fiber, and the family of plastics known as acrylics, and polytetrafiuoroethylene. The electrical element 26 and insulating member 30 are both cylindrical and have substantially the same diameter. In the figures, the insulating member 30 is secured to the element by means of a ball shaped connector 32 which is inserted into an opening 34 in the end of the electrical element 26. This type of connection is shown by way of example only since any means may be used to secure the insulating member 30 on the element 26.

The bushing is mounted on a panel or wall by inserting elongated end 48 through an opening 50 in a wall 52 and screwing a nut 51 onto the threaded section 46. A gasket 53 may be provided between the wall and bushing to seal the bushing to the Wall. An O-ring seal may be provided on the end of the threaded section to provide a fluid-type mounting if the bushing is mounted in the side Wall of an oil-filled transformer. An electrically conductive conductor 54 is coaxially mounted in the bushing and is provided with a threaded recess 56 for connection to a high voltage line. A second electrically conductive element or sleeve '58 is positioned within recess 42 and is connected to conductor 54 by a screw 60. A small diameter section 62 is provided at the end of the sleeve 58 to electrically engage the conductive element or member 26. Slots 64 may be provided in the sleeve 58 to allow for a certain amount of flexure at the reduced diameter section of the sleeve 58. An arc extinguishing electrically non-conductive sleeve or insulating means 66 is positioned at the end of the recess and abuts the end of the electrically conductive sleeve 58. The inside diameter of the sleeve 58 is slightly larger than the outside diameter of the member 26 to provide a snug fit between the two insulating members 14 and 16.

The elongated section of the bushing is tapered at the same angle as the taper in recess 16 in the plug. A snug fit is, therefore, provided between the receptacle and plug and is moisture proofed by coating the surfaces with a grease-like material prior to connection of the plug and receptacle. A groove 38 may be provided near the end of the elongate section which engages annular projection 36 in recess 16 to hold the plug and receptacle in engagement. The annular groove cooperates with the ring in the plug to provide a holding or looking action when the plug is fully seated in the receptacle. The snug fit between the plug and receptacle will also provide some holding action due to the vacuum set up between the plug and receptacle when a force is applied to disconnect them. When the plug is disconnected from the receptacle, a force will be applied to the hook eye and either the ring and groove or the snug fit of the plug and receptacle or both will initially prevent disconnection, causing a slight elongation of the plug due to its elastic characteristic. When the disconnecting force is sufiicient to overcome this holding action, the plug will disconnect from the receptacle with a snap action due to the energy stored in elongating the lug.

p In connecting the plug and receptacle, insulating member 30 is telescopically inserted in sleeve 66 and the elongated section 48 is aligned with recess 16. The plug is then pushed onto the receptacle until the end of member 26 is telescoped into mating engagement with the reduced diameter section 62 of the sleeve 58 and electrically engages the end of member 26. The inner end of the elongated section will then be seated in the recess with the inwardly projecting section seated in the groove of the receptacle.

Normally, when the plug is withdrawn from the receptacle, a gap will occur between the electrically conductive element 26 and the electrically conductive sleeve 58 across which a high voltage arc will be established. With the insulating member 30 being pulled into the insulating sleeve 66 as the plug is withdrawn from the elongated section, the heat of the are drawn between the conductive members will be confined to the small space between the insulating member and sleeve. The heat of the arc will generate a de-ionized atmosphere from the insulating member 30 and sleeve 66 which will interrupt the load current in the gap, thus extinguishing the arc.

In FIGS. 3 and 4 a modified arrangement is shown which can be used to accomplish the same result. The receptacle is shown in phantom and is provided within a non-conductive insulating sleeve 70 forming an extension of the end of an electrically conductive sleeve or element 72 within recess 74. An electrically non-conductive cap 76 is positioned within the electrically conductive sleeve 72 and is biased by spring 78 outwardly of the sleeve 72. An outwardly projecting flange 80 is provided at the open end of the cap 72 to engage the reduced diameter section 82 of the sleeve to retain the cap within the sleeve. When the plug is pushed onto the receptacle, the end of electrically conductive element 84 will force the cap 76 into the sleeve 72 against the compressive force of the spring 78. No electrical connection will be made until the end of the conductive element engages the reduced diameter section of the sleeve 72. In disconnection, the electrically-conductive element 84 is withdrawn from the sleeve 72 and the cap follows the motion of the conductor as it is pulled out of the sleeve 72. The cap will, therefore, provide a high dielectric medium in the gap between the two conductors, extinguishing any arc produced.

Although only two modifications of the invention have been shown and described, it should be obvious that changes in the design of the plug and receptacle and the cooperation of the insulated members can be made Without departing from the scope of the disclosed invention.

What is claimed is:

1. An electrical connector for disconnecting high voltage conductors comprising a first insulating member having a connection recess with an inner surface,

a first electrically conductive element mounted in said first member and projecting in said recess,

said conductive element being adapted for connection to a high voltage conductor, and

a second insulating member having a connection inlet and an outer surface conforming to said connection recess inner surface to produce a seal on insertion of said second member into said connection recess,

a second electrically conductive element positioned in said connection inlet for engagement with said first conductive element on insertion of said first electrically conductive element into said inlet,

an electrically non-conductive sleeve positioned adjacent to the entry end of said inlet,

and insulating means of arc extinguishing material associatedewith said first conductive element in aposition 'to'cooperate' with said non-conductive sleeve r when 'said' first "conductive element. is being. withdrawn from said second conductiveelement-to inter.- rupt the. load currentin the :gap between'the two elements. 2. An electrical connector according to-claim l 'wherein said insulating means includes an elongate member Secured to said first conductive element-to follow said first conductive element through said sleeve when said first insulating member, is disconnected from-said second insulatingmember.

'3. An electrical connector according to claim- 1 Wherein said insulating means includes a. cap mountedfor reciprocal motion within said conductive sleeve and: spring means for biasing the cap outward from said second conductive element. 1 4. An-electrical connector according to claim 1 wherein said interior surface is'tapered and said outer-surface is tapered. 5. An electrical connector comprising t ea-first insulating member having a recess-with an inne 'surface, I a firstelectrically conductive element mounted in said first member and projecting axially'into said recess, means for connecting said-first conductive element to a high voltage conductor, 1 a second insulating member having an elongate section shaped for insertion into said recess :and having an: opening for receiving said first conductive element, saidelongate section havingan oute'rsurface conformable to-said inner surface of said recess to form a seal'on connection,

an electrically conductive sleeve positioned within said opening for electrical engagement with said first conductive element,

a first insulating means of arc extinguishing material positioned adjacent to the entry end of said opening for initial engagement with said first conductive element on insertion into said opening,

and a second insulating means of arc extinguishing .ma-

terial mounted on the end of said first conductive element to engage said first insulating means first on insertion of said first conductive element into said conductive sleeve and to engage said first insulating means last \as said conductive element is withdrawn from said conductive sleeve.

6. An electrical connector according to claim 5 wherein said inner surface of said recess and said outer surface of said elongate section are coated with a grease-like material thereby to improve the moisture seal formed around said electrically conductive element and sleeve.

7. An electrical connector according to claim 5 wherein said first insulating member has a stress cone-shaped section for cable termination.

8. An electrical connector according to claim 5 wherein said inner surface is tapered and said outer surface is tapered.

9. An electrical connector comprising a first insulating member having a first recess,

an electrically conductive element mounted in said first member and projecting in said recess, said element being connected to a high voltage conductor,

a second insulating member having an elongate section shaped for mating engagement with said first recess, said second member including an electrically conductive sleeve adapted to be connected to a high voltage apparatus,

first insulating means of arc extinguishing material mounted :adjacent to the entry end of said sleeve for engagement with said conductive element on insertion of said conductive element into said sleeve, and

a second insulating means of arc extinguishing material mounted on said conductive element for engagement with said first insulating means on insertion of said conductive element into said sleeve and for engagement vwith said first insulating means last on withdrawal of said conductive element from said sleeve. 10. An electrical connector according to claim 9 wherein said first insulating member is formed from an elastic insulating material and includes holding means for engaging said second insulating member,

whereby on withdrawal of said first member from said second member, a snap action disconnection will be provided between the conductive member and the sleeve.

11. A connector according to claim 10 wherein said holding means comprises an :annular ring in said recess and an annular groove in said elongate shaped section located in a position to engage said ring on insertion of said section into said recess.

connector comprising :a pair of insulating members, one of said members having a connection recess with an inner surface and the other of said members having a connection inlet and an outer surface conforming to said inner surface of said connection recess to produce a seal on insertion of said other of said members into said connection recess,

a pair of telescopically mating electrically conductive contacts supported by said insulating members,

a pair of telescopically mating elements of arc extinguishing material associated with said pair of conductive contacts to momentarily move into the arc path between said conductive contacts when separated, one of said elements being a sleeve and the other of said elements being insertable into said sleeve,

at least one of said insulating members being of an elastomeric material to form the seal with the other insulating member, and

means for connecting said conductive pair of contacts to high voltage conductors.

13. A connector according to claim 12 wherein said inner surface is tapered and said outer surface is tapered for mating engagement with said inner surface.

14. In combination, a first insulating member having a recess,

a first electrically conductive element supported by said first member and projecting into said recess,

means for connecting said first conductive element to a high voltage conductor,

an arc extinguishing member secured to said first electrically conductive element, and

a second insulating member having an elongate section shaped to sealingly engage said recess and a connection inlet to receive said first electrically conductive element,

a second electrically conductive element positioned in said inlet to electrically engage said first conductive element,

means for connecting said second electrically conductive element to a second high voltage conductor,

a sleeve of arc extinguishing material positioned adjacent to the entry end of said connection inlet to engage said are extinguishing member first on insertion of said first conductive element into said conductive sleeve.

15. The combination according to claim 14 wherein said elongate section forms a vacuum seal on disconnection of said section from said recess and one of said insulating members is formed from a resilient material which elongates on disconnection to 7 provide a snap release of the electrically conductive elements on disconnection. 16. The combination according to claim 14 including an annular ring in said recess and an annular groove in said section.

2,677,115 4/1954 Stevens 339--111 X 4/1943 Triplett 200-449 8 3,124,405 3/1964 Massa 339-75 X 3,277,424 10/1966 Nelson 33994 3,281,560 10/1966 Nava 200149 X FOREIGN PATENTS 1,273,012 8/1961 France.

RICHARD E. MOORE, Primary Examiner US. Cl. X.R. 339-111 

